Spatial Reference Manual
Page 55 of 158
Version 4.4
04/06/2019
on top of a 2D or 3D calibration it can give the best results from magnetic heading.
Every time Spatial is powered on in a cold start (48 hours without power) the
automatic calibration is reset. The automatic magnetic calibration starts operating
when Spatial is travelling at a speed over 5 m/s with a GNSS fix and velocity heading
turned on. Automatic magnetic calibration is not as accurate as 2D or 3D calibration,
however it is sufficient for most vehicles and allows Spatial to be installed into vehicles
and operated without user intervention. Automatic magnetic calibration can be turned
off using the filter options dialogue in Spatial Manager, see section 11.8.3.
10.5.4
Disabling Magnetometers
In situations where there is very strong dynamic magnetic disturbances present, it is
recommended to disable the magnetometers. When the magnetometers are disabled
a secondary heading source is required otherwise may become inaccurate. Velocity
heading is the recommended source. Please see section 10.4 for information on
heading sources. The magnetometers can be disabled using the filter options dialogue
in Spatial Manager, see section 11.8.3.
10.6 Sensors Range
Spatial supports dynamic ranging on its sensors. Each of the three sensors have three
different range levels. At lower ranges the sensor performance is better, but at higher
ranges Spatial can be used in more extreme dynamics. It is important to choose a
range that your application won't exceed.
Sensor over range events can be detected through the Filter Status. In Spatial
manager the status indicator will go orange indicating that a sensor has gone over
range. When a sensor goes over range this causes the filter solution to become
inaccurate and in some cases it can cause the filter to reset.
By default Spatial comes configured in the lowest sensor ranges. In this configuration
it is possible to send the gyroscopes over range by quickly rotating the unit in your
hand. It is recommended to watch what happens in Spatial Manager when you do this.
The sensor ranges can be set through the sensor ranges dialogue in the configuration
menu in Spatial Manager, see section 11.8.2.
10.7 Data Anti Aliasing
Internally Spatial's filters update at 1000 Hz. When Spatial outputs data, most
applications require the data at a much lower rate (typically < 100 Hz). This causes a
problem for time based data such as velocities and accelerations where aliasing will
occur at the lower rate. To prevent this problem, if the output rate is lower than 1000
Hz, Spatial will low pass filter the values of the time dependent data between packets
to prevent aliasing. This is only the case when a packet is set up to output at a certain
rate. If the packet is simply requested no anti aliasing will occur. Additionally there is
no anti aliasing for non time dependent fields such as position.
10.8 Vehicle Profiles
Spatial supports a number of different vehicle profiles. These vehicle profiles impose
